Magnetic Fields, Relativistic Particles, and Shock Waves in Cluster Outskirts

It is only now, with low-frequency radio telescopes, long exposures with high-resolution X-ray satellites and γ-ray telescopes, that we are beginning to learn about the physics in the periphery of galaxy clusters. In the coming years, Sunyaev-Zel’dovich telescopes are going to deliver further great insights into the plasma physics of these special regions in the Universe. The last years have already shown tremendous progress with detections of shocks, estimates of magnetic field strengths and constraints on the particle acceleration efficiency. X-ray observations have revealed shock fronts in cluster outskirts which have allowed inferences about the microphysical structure of shocks fronts in such extreme environments. The best indications for magnetic fields and relativistic particles in cluster outskirts come from observations of so-called radio relics, which are megaparsec-sized regions of radio emission from the edges of galaxy clusters. As these are difficult to detect due to their low surface brightness, only few of these objects are known. But they have provided unprecedented evidence for the acceleration of relativistic particles at shock fronts and the existence of μG strength fields as far out as the virial radius of clusters. In this review we summarise the observational and theoretical state of our knowledge of magnetic fields, relativistic particles and shocks in cluster outskirts.     

The Interstellar Boundary Explorer (IBEX):

The Interstellar Boundary Explorer (IBEX) mission is exploring the frontiers of the heliosphere where energetic neutral atoms (ENAs) are formed from charge exchange between interstellar neutral hydrogen atoms and solar wind ions and pickup ions. The geography of this frontier is dominated by an unexpected nearly complete arc of ENA emission, now known as the IBEX ‘Ribbon’. While there is no consensus agreement on the Ribbon formation mechanism, it seems certain this feature is seen for sightlines that are perpendicular to the interstellar magnetic field as it drapes over the heliosphere. At the lowest energies, IBEX also measures the flow of interstellar H, He, and O atoms through the inner heliosphere. The asymmetric oxygen profile suggests that a secondary flow of oxygen is present, such as would be expected if some fraction of oxygen is lost through charge exchange in the heliosheath regions. The detailed spectra characterized by the ENAs provide time-tagged samples of the energy distributions of the underlying ion distributions, and provide a wealth of information about the outer heliosphere regions, and beyond.     

Earth's earliest biosphere-a proposal to develop a collection of curated archean geologic reference materials

The discovery of evidence indicative of life in a Martian meteorite has led to an increase in interest in astrobiology. As a result of this discovery, and the ensuing controversy, it has become apparent that our knowledge of the early development of life on Earth is limited. Archean stratigraphic successions containing evidence of Earth's early biosphere are well preserved in the Pilbara Craton of Western Australia. The craton includes part of a protocontinent consisting of granitoid complexes that were emplaced into, and overlain by, a 3.51-2.94 Ga volcanigenic carapace - the Pilbara Supergroup. The craton is overlain by younger supracrustal basins that form a time series recording Earth history from approximately 2.8 Ga to approximately 1.9 Ga. It is proposed that a well-documented suite of these ancient rocks be collected as reference material for Archean and astrobiological research. All samples would be collected in a well-defined geological context in order to build a framework to test models for the early evolution of life on Earth and to develop protocols for the search for life on other planets.     

The first cell membranes

Organic compounds are synthesized in the interstellar medium and can be delivered to planetary surfaces such as the early Earth, where they mix with endogenous species. Some of these compounds are amphiphilic, having polar and nonpolar groups on the same molecule. Amphiphilic compounds spontaneously self-assemble into more complex structures such as bimolecular layers, which in turn form closed membranous vesicles. The first forms of cellular life required self-assembled membranes that were likely to have been produced from amphiphilic compounds on the prebiotic Earth. Laboratory simulations show that such vesicles readily encapsulate functional macromolecules, including nucleic acids and polymerases. The goal of future investigations will be to fabricate artificial cells as models of the origin of life.     

美国开始进行长航时无人机的武器投放试验

普罗透斯又称"希腊海神"飞机,是由美国缩比复合材料公司研制的,早先曾被用于科学仪表测试,后来被广泛用于美国防部中空长航时无人机性能试验和其他先进技术的验证工作,并成为一种在无人机发展项目中的低风险、相对廉价的试验飞机.     

E-10机载雷达与高能微波武器

如今的MP—RTIP雷达不仅可对如巡航导弹大小的隐身目标进行定位和瞄准,还可直接作为攻击性电子战武器使用;高能微波武器的精确性要求比激光武器低,成本又比之低廉。这些性能优势使它们在定向能武器发展方向上迅速超越激光武器,成为研发人员高度关注的技术领域之一。     

Commercial spaceports — a window of opportunity?

The feasibility of building commercial spaceports is being actively investigated in several countries. Potential benefits include boosting economic development and assisting the commercial launch industry. This report finds, however, that commercial spaceport development will probably not be capable of generating a large enough return on investment to attract private sector involvement without significant government assistance. It is also unlikely that the market for large launch vehicles will support spaceport development; however, small satellites may offer better prospects.     

探索中的电子战

在不久的将来,采用硅电子和光子集成电路的计算机、针头大小射频发射器,加上小尺寸无人机的使用,将大大提升电子战和信息战的能力。美国和英国作战人员认为,电子战将是未来的信息战的支柱,而决定未来电子战成败的两大关键技术是,电子探测能力和电子攻击能力。     

Direct observation of charge state abundances of energetic He,C, O,and Fe emitted in solar flares

The ionic charge states of helium, carbon, oxygen, and iron have been determined for three solar particle enhancements by an electrostatic deflection analyzer, which is combined with a thin window proportional counter dE/dX vs. E system. The observations are obtained during the periods September 23 to 29, 1978, June 6 to 8, 1979, and September 15 to 26, 1979, with an instrument onboard the ISEE-3 spacecraft. The mean ionic charge states for He, C, and oxygen exhibit a high degree of ionization with values of Q = 2, 6, and 7.2, respectively. The charge state of iron is near 13 charge units. Variations from flare to flare and within the September 23, 1978 flare are small. The most surprising feature of the charge state measurement is the observation of a small (～10%) but finite contribution of singly ionized helium.